* [PATCH] perf/stat: fix bug in handling events in error state
@ 2017-04-12 18:23 David Carrillo-Cisneros
2017-04-13 8:28 ` Jiri Olsa
2017-04-17 8:34 ` [tip:perf/core] perf stat: Fix " tip-bot for Stephane Eranian
0 siblings, 2 replies; 3+ messages in thread
From: David Carrillo-Cisneros @ 2017-04-12 18:23 UTC (permalink / raw)
To: linux-kernel
Cc: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Alexander Shishkin, Jiri Olsa, Wang Nan, Andi Kleen,
Adrian Hunter, Mathieu Poirier, Stephane Eranian, Paul Turner,
David Carrillo-Cisneros
From: Stephane Eranian <eranian@google.com>
(This is a patch has been sitting in the Intel CQM/CMT driver series
for a while, despite not depend on it. Sending it now independently
since the series is being discarded.)
When an event is in error state, read() returns 0
instead of sizeof() buffer. In certain modes, such
as interval printing, ignoring the 0 return value
may cause bogus count deltas to be computed and
thus invalid results printed.
This patch fixes this problem by modifying read_counters()
to mark the event as not scaled (scaled = -1) to force
the printout routine to show <NOT COUNTED>.
Signed-off-by: Stephane Eranian <eranian@google.com>
Reviewed-by: David Carrillo-Cisneros <davidcc@google.com>
---
tools/perf/builtin-stat.c | 12 +++++++++---
tools/perf/util/evsel.c | 4 ++--
2 files changed, 11 insertions(+), 5 deletions(-)
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 688dea7cb08f..c3c4b4990f3c 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -310,8 +310,12 @@ static int read_counter(struct perf_evsel *counter)
struct perf_counts_values *count;
count = perf_counts(counter->counts, cpu, thread);
- if (perf_evsel__read(counter, cpu, thread, count))
+ if (perf_evsel__read(counter, cpu, thread, count)) {
+ counter->counts->scaled = -1;
+ perf_counts(counter->counts, cpu, thread)->ena = 0;
+ perf_counts(counter->counts, cpu, thread)->run = 0;
return -1;
+ }
if (STAT_RECORD) {
if (perf_evsel__write_stat_event(counter, cpu, thread, count)) {
@@ -336,12 +340,14 @@ static int read_counter(struct perf_evsel *counter)
static void read_counters(void)
{
struct perf_evsel *counter;
+ int ret;
evlist__for_each_entry(evsel_list, counter) {
- if (read_counter(counter))
+ ret = read_counter(counter);
+ if (ret)
pr_debug("failed to read counter %s\n", counter->name);
- if (perf_stat_process_counter(&stat_config, counter))
+ if (ret == 0 && perf_stat_process_counter(&stat_config, counter))
pr_warning("failed to process counter %s\n", counter->name);
}
}
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 8bc271141d9d..d54efb5ee8bc 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1221,7 +1221,7 @@ int perf_evsel__read(struct perf_evsel *evsel, int cpu, int thread,
if (FD(evsel, cpu, thread) < 0)
return -EINVAL;
- if (readn(FD(evsel, cpu, thread), count, sizeof(*count)) < 0)
+ if (readn(FD(evsel, cpu, thread), count, sizeof(*count)) <= 0)
return -errno;
return 0;
@@ -1239,7 +1239,7 @@ int __perf_evsel__read_on_cpu(struct perf_evsel *evsel,
if (evsel->counts == NULL && perf_evsel__alloc_counts(evsel, cpu + 1, thread + 1) < 0)
return -ENOMEM;
- if (readn(FD(evsel, cpu, thread), &count, nv * sizeof(u64)) < 0)
+ if (readn(FD(evsel, cpu, thread), &count, nv * sizeof(u64)) <= 0)
return -errno;
perf_evsel__compute_deltas(evsel, cpu, thread, &count);
--
2.12.2.715.g7642488e1d-goog
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] perf/stat: fix bug in handling events in error state
2017-04-12 18:23 [PATCH] perf/stat: fix bug in handling events in error state David Carrillo-Cisneros
@ 2017-04-13 8:28 ` Jiri Olsa
2017-04-17 8:34 ` [tip:perf/core] perf stat: Fix " tip-bot for Stephane Eranian
1 sibling, 0 replies; 3+ messages in thread
From: Jiri Olsa @ 2017-04-13 8:28 UTC (permalink / raw)
To: David Carrillo-Cisneros
Cc: linux-kernel, Peter Zijlstra, Ingo Molnar,
Arnaldo Carvalho de Melo, Alexander Shishkin, Wang Nan,
Andi Kleen, Adrian Hunter, Mathieu Poirier, Stephane Eranian,
Paul Turner
On Wed, Apr 12, 2017 at 11:23:01AM -0700, David Carrillo-Cisneros wrote:
> From: Stephane Eranian <eranian@google.com>
>
> (This is a patch has been sitting in the Intel CQM/CMT driver series
> for a while, despite not depend on it. Sending it now independently
> since the series is being discarded.)
>
> When an event is in error state, read() returns 0
> instead of sizeof() buffer. In certain modes, such
> as interval printing, ignoring the 0 return value
> may cause bogus count deltas to be computed and
> thus invalid results printed.
>
> This patch fixes this problem by modifying read_counters()
> to mark the event as not scaled (scaled = -1) to force
> the printout routine to show <NOT COUNTED>.
>
> Signed-off-by: Stephane Eranian <eranian@google.com>
> Reviewed-by: David Carrillo-Cisneros <davidcc@google.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
thanks,
jirka
^ permalink raw reply [flat|nested] 3+ messages in thread
* [tip:perf/core] perf stat: Fix bug in handling events in error state
2017-04-12 18:23 [PATCH] perf/stat: fix bug in handling events in error state David Carrillo-Cisneros
2017-04-13 8:28 ` Jiri Olsa
@ 2017-04-17 8:34 ` tip-bot for Stephane Eranian
1 sibling, 0 replies; 3+ messages in thread
From: tip-bot for Stephane Eranian @ 2017-04-17 8:34 UTC (permalink / raw)
To: linux-tip-commits
Cc: mathieu.poirier, jolsa, acme, linux-kernel, pjt, wangnan0, ak,
davidcc, mingo, peterz, tglx, alexander.shishkin, adrian.hunter,
hpa, eranian
Commit-ID: db49a71798a38f3ddf3f3462703328dca39b1ac7
Gitweb: http://git.kernel.org/tip/db49a71798a38f3ddf3f3462703328dca39b1ac7
Author: Stephane Eranian <eranian@google.com>
AuthorDate: Wed, 12 Apr 2017 11:23:01 -0700
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Thu, 13 Apr 2017 10:40:36 -0300
perf stat: Fix bug in handling events in error state
(This is a patch has been sitting in the Intel CQM/CMT driver series for
a while, despite not depend on it. Sending it now independently since
the series is being discarded.)
When an event is in error state, read() returns 0 instead of sizeof()
buffer. In certain modes, such as interval printing, ignoring the 0
return value may cause bogus count deltas to be computed and thus
invalid results printed.
This patch fixes this problem by modifying read_counters() to mark the
event as not scaled (scaled = -1) to force the printout routine to show
<NOT COUNTED>.
Signed-off-by: Stephane Eranian <eranian@google.com>
Reviewed-by: David Carrillo-Cisneros <davidcc@google.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/20170412182301.44406-1-davidcc@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/builtin-stat.c | 12 +++++++++---
tools/perf/util/evsel.c | 4 ++--
2 files changed, 11 insertions(+), 5 deletions(-)
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 868e086a..610225b 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -312,8 +312,12 @@ static int read_counter(struct perf_evsel *counter)
struct perf_counts_values *count;
count = perf_counts(counter->counts, cpu, thread);
- if (perf_evsel__read(counter, cpu, thread, count))
+ if (perf_evsel__read(counter, cpu, thread, count)) {
+ counter->counts->scaled = -1;
+ perf_counts(counter->counts, cpu, thread)->ena = 0;
+ perf_counts(counter->counts, cpu, thread)->run = 0;
return -1;
+ }
if (STAT_RECORD) {
if (perf_evsel__write_stat_event(counter, cpu, thread, count)) {
@@ -338,12 +342,14 @@ static int read_counter(struct perf_evsel *counter)
static void read_counters(void)
{
struct perf_evsel *counter;
+ int ret;
evlist__for_each_entry(evsel_list, counter) {
- if (read_counter(counter))
+ ret = read_counter(counter);
+ if (ret)
pr_debug("failed to read counter %s\n", counter->name);
- if (perf_stat_process_counter(&stat_config, counter))
+ if (ret == 0 && perf_stat_process_counter(&stat_config, counter))
pr_warning("failed to process counter %s\n", counter->name);
}
}
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 8f5d86b..3779b9f 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1239,7 +1239,7 @@ int perf_evsel__read(struct perf_evsel *evsel, int cpu, int thread,
if (FD(evsel, cpu, thread) < 0)
return -EINVAL;
- if (readn(FD(evsel, cpu, thread), count, sizeof(*count)) < 0)
+ if (readn(FD(evsel, cpu, thread), count, sizeof(*count)) <= 0)
return -errno;
return 0;
@@ -1257,7 +1257,7 @@ int __perf_evsel__read_on_cpu(struct perf_evsel *evsel,
if (evsel->counts == NULL && perf_evsel__alloc_counts(evsel, cpu + 1, thread + 1) < 0)
return -ENOMEM;
- if (readn(FD(evsel, cpu, thread), &count, nv * sizeof(u64)) < 0)
+ if (readn(FD(evsel, cpu, thread), &count, nv * sizeof(u64)) <= 0)
return -errno;
perf_evsel__compute_deltas(evsel, cpu, thread, &count);
^ permalink raw reply related [flat|nested] 3+ messages in thread
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2017-04-13 8:28 ` Jiri Olsa
2017-04-17 8:34 ` [tip:perf/core] perf stat: Fix " tip-bot for Stephane Eranian
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